【作者】 赵立东；

【导师】 谭忆秋；

【作者基本信息】 哈尔滨工业大学 ， 道路与铁道工程， 2012， 博士

【摘要】 我国南方云南、贵州、四川等省地处高海拔潮湿山区，由于气候条件和地理位置等原因，冬季或早春时节经常出现凝冻灾害。凝冻天气会导致路面产生凝冰，不但会严重影响道路交通安全和运输效率，还会直接或间接造成路面本身的严重损坏。由于凝冻天气条件的特殊性，其对沥青路面造成的损坏有别于我国北方等季冻区冬季温度和湿度持续较低的气候特点对路面造成的损坏，目前针对沥青路面凝冰损坏的相关研究也较少。鉴于此，本文针对南方高原潮湿山区凝冻天气对沥青路面造成的损坏，开展其损坏特点、影响因素、细观机理以及评价方法等方面的研究，从而为这些地区沥青路面凝冰前防护、凝冰后修复以及抗凝冰损坏路面材料的设计等工作提供依据。首先，通过现场调查、检测，结合芯样试验分析了凝冰对沥青路面使用性能和混合料组成结构的影响，结果表明：凝冰破坏作用主要影响路面表面状况，使其集料剥落、形成麻面等病害，路面构造深度增大。通过对凝冰损坏不同程度路面的检测和芯样试验，分析沥青路面抗凝冰损坏能力存在差异的材料特性，结果表明：混合料空隙率、矿料间隙率、沥青饱和度、集料表面沥青膜厚度，集料强度、与沥青的低温粘结性等性质都会影响沥青路面抗凝冰损坏能力。然后，根据现场调研结果，开展了沥青混合料凝冰损坏影响因素研究。单面冻融试验和低温飞散试验表明：空隙率对混合料受凝冰作用，以及受凝冰和交通荷载共同作用的损坏程度有重要影响，提出了AC-16混合料抗凝冰损坏需控制的临界空隙率为6%。鉴于空隙对混合料凝冰损坏的重要影响，采用工业CT试验、图像处理技术、有限元等方法揭示了空隙率及空隙分布状态对沥青混合料凝冰损坏、交通荷载加剧混合料损坏的影响机理。此外，分析了其它影响沥青路面受凝冰和交通荷载共同作用损坏的内在因素，结果表明：SMA-13混合料抗凝冰损坏效果优于AC-13和AC-16，两种AC混合料相差不大；与基质沥青相比，改性沥青对混合料凝冰后的抗集料剥落能力有显著提高，且冻融次数越多优势越明显；在空隙率一致的情况下，玄武岩混合料抗凝冰和交通荷载冲击、磨耗能力优于石灰岩混合料。鉴于沥青路面行车道交通荷载会加剧路面凝冰损坏，采用限元模拟分析了交通荷载加剧混合料凝冰损坏的机理。结果表明：空隙内动水冲刷作用对不同位置沥青砂浆和沥青膜的受力和变形有加剧或减弱的作用，整体上会加剧混合料损坏；空隙中水结冰产生的冻胀力作用会明显造成或加剧沥青混合料损坏。再后，鉴于凝冰后沥青路面麻面、松散等病害与沥青胶浆-集料间的粘结特性有密切关系，开发了“沥青胶浆-未处理集料粘结特性的拉拔试验”方法，揭示了凝冰对混合料胶浆-集料粘结结构的损坏机理。结果表明：①水的浸入使得沥青胶浆-集料粘结的破坏形式由粘聚破坏变为粘附破坏，且破坏荷载大大降低，在冰膨胀力最大的-4℃时对路面损坏最显著。②若胶浆与集料界面无水浸入，则冻融作用对其无明显破坏作用；若界面有水浸入，冻融初期即对界面粘结力产生严重的破坏作用，界面很快脱粘。并从沥青胶浆-集料粘结特性角度揭示了原材料对混合料凝冰损坏的影响机理：SBS改性沥青优于基质沥青，界面有水时优势更明显；粉胶比应控制在0.7～1.3范围内；温度约-4℃以上时，石灰岩与沥青胶浆粘结性能受界面冰冻胀作用的影响稍小于玄武岩，但温度约-4℃以下时，两种集料相差不大。最后，针对沥青路面仅受凝冻作用时损坏具有隐蔽性，开发了用于检测沥青路面表面层集料剥落程度的“沥青路面冻融损坏现场快速检测设备”，并验证了采用该设备测得的单位面积剥落量评价沥青路面凝冰损坏程度具有良好的敏感性。结合现场调查结果，针对贵州地区沥青路面上面层AC-16混合料，提出了“快速检测设备”测得的临界单位面积质量损失为0.4g/cm~2，可为当地沥青路面凝冰损坏修复工作提供依据。更多还原

【Abstract】 In Yunnan, Guizhou, Sichuan, and other high altitude humid mountain areas,freezing disaster appears very commonly in winter or early spring due to localclimatic and geographical conditions. Condensate ice would appear on pavementbecause of freezing disaster, which not only affect the traffic safety and transportefficiency adversely, but also damage the asphalt pavement performance seriouslydirectly or indirectly. The damage forms and characteristics of pavement caused bycondenstare ice are significantly different from the cold regions of northern China,where continuous low temperature and humidity in winter. At present, theresearches about pavement damage caused by condensate ice is also less. Therefore,the researches were carried out focusing on the asphalt pavement damages causedby condensate ice in high altitude humid mountain areas, which included thedamage characteristics, influencing factors, microscopic mechanism and evaluationmethod. The conclusions could provide a basis for pavement curing after freezingdisaster, and pavement materials design resisting condensate ice damage in theseareas.Firstly, field invertigation, detection and core samples tests of typical pavementwere carried out to analyze the effect of condensate ice on pavement performanceand mixture composition structure. The results showed that the main effect ofcondensate ice are on the pavement surface conditions, which lead to aggregatestripping off, forming surface pockmark, loosening diseases, and increasing thesurface textuer depth.The materials features of different ability pavemets in resistingcondensate ice damage were analysed, which had gone through the same freezingdisaster, but showed differernt externt of damage. The results indicate that the voidratio, voids in mineral aggregate, asphalt saturation degree and the firm thicknessaround aggregate would influence the ability of mixture resisting condensate icedamage. And the aggregate strength, adhesion with asphalt at low temperatureinfluence mixture damage aslo.Secondly, the main factors of mixture damage caused by condensate ice wereresearched in this paper, and the void was considered to be the most importantfactor. Single-side freeze-thaw test and ravelling test at low temperature of mixtures indicate that the initial void ratio will impact seriously on pavement condensate icedamage. The critical void ratio6%of AC-16mixture resisting condensate icedamage is proposed. Since void could impact mixture performance seriously, themechanism of void ratio and void distribution impacting on mixture damage causedby condensate ice, or condensate ice and vehicle load together were revealed basiedon CT tests, image processing technology finite element method. Addition, otherfators of mixture subjecting from condensate ice and vehicle load were researchedalso. SMA-13mixture is superior to the AC-13and AC-16mixtures, and the twoAC mixtures are similar. Compared with common asphalt, modified asphalt couldimprove significantly aggregate anti-stripping capacity after freeze-thaw, and morenumbers of freeze-thaw, the advantages more obvious. Basalt is better thanlimestone in mixture resisting frost swelling, vehicle striking and polishing in thecase of mixtues with the same void ratio.As the vehicle load could seriously aggravate the asphalt pavement condensateice damage, the mechanism was simulated using finite element method. The stressof different location mortar and asphalt film may be exacerbated or diminished bydynamic water pressure, but would exacerbate mixture damage overall. And waterfrost swelling in void would cause or aggravate the mixture destruction obviously.Thirdly, since the surface pockmark and loosening diseases of pavement areclosely associated with the bonding properties between asphalt and aggregate.“pull-off test about asphalt paste-untreated aggregate bonding properties” wasdeveloped to reveal the meso mechanism of asphalt pavement damage caused bycondensate ice according actual pavement condition. Some results can be obtained.①The destruction stype of asphalt paste-aggregate bonding structure becomesadhesion failure from cohesion failure because of water immersion, and the failureload reduces greatly. And the pavement damage most seriously at-4℃.②Thepaste-aggregate bonding structure would be impacted slightly by freeze-thaw ifthere is no water in the interface; while the bonding interface would debond quicklyin early freeze-thaw if water had immersed to interface.The effects of raw material on mixture condensate ice damage were verified inthe meso view of asphalt paste-aggregate bonding structure. SBS modified asphaltis better than common asphalt, and the advantage is more obvious if water esists ininterface. Filler-asphalt ratio should be controlled between0.7and1.3. Basaltaggregate is better than limestone in bonding with asphalt paste at above about-4℃ if suffered from water frost swelling in interface, but the bonding properties of thetwo kinds of aggregates are similar under about-4℃.At last, as the damage of asphalt pavemen caused by condensate ice only isundercover, the “fast testing equipment of asphalt pavement freeze-thaw damage”was developed to detect the degree of aggregate stripping off according to thedamage form and characteristics. And verify the mass per unit area of stripped offaggregate is sensitive in evaluating the condensate ice damage degree of asphaltpavement. Combined with the field results,0.4g/cm~2is proposed as the criticalmass loss per unit area detected by “fast testing equipment” focusing on AC-16mixture of Guizhou region asphalt pavement top layer, which could procid basis forrapair work of local pavement damage after condensate ice.更多还原